macro_rules! roots {
(@build [$($acc:tt)*]) => { ... };
(@build [$($acc:tt)*]
#[doc = $_a:literal] #[doc = $_b:literal] $path:literal $(, $($rest:tt)*)?
) => { ... };
(@build [$($acc:tt)*]
#[doc = $label:literal] $path:literal $(, $($rest:tt)*)?
) => { ... };
(@build [$($acc:tt)*] $path:literal $(, $($rest:tt)*)?) => { ... };
( $($t:tt)* ) => { ... };
}